The ultimate aim of this project is to explain the functional sparing seen in mammals sujected to brain damage in infancy. Two specific problems are being studied: 1) environmental factors which favor or militate against sparing after visual cortical lesions and 2) possible differences in the rate which different cortical regions establish their anatomical connections. Cats with 1- or 2-stage ablations of areas 17, 18 and 19 made in infancy or in adulthood are being tested for pattern discrimination in three different test situations, and their depth perception and visual acuity is being assessed. The development of connections to the visual and auditory cortex is being determined pre- and postnatally with tritiated proline and HRP.